An interactive system is one which presents to a user a program taken from a number of predefined response programs selected on the basis of the user's inputs. Examples are found in interviewing machines, teaching machines, and interactive games.
Prior systems usually employed prerecorded questions and responses, each on a different magnetic tape which were selected and played back in response to simple user inputs. The number of different responses was limited by the number of magnetic tape players that could be packaged in a system.
In some cases the responses and questions were recorded sequentially in segments on a single tape and the tape was run in either direction to search for a particular segment. That scheme involves variable delays between the time of input and response because search time is a function of the position which the segment to be played occupied along the length of the tape.
In the case of video tape, the size and cost of play back units was sufficiently great to make the use of multiple players prohibitive. Most video output machines employ a single tape or disc, or a single film, and they resort to searching for the required segments.
The time delay can not be tolerated in the case of video games. The game machines abandoned analog techniques and employed digital information instead. The display was limited to "stick men," to vertical or horizontal movement on the display screen, to localized increases in brilliance, and other simplistic representations. Early games utilized a limited number of responses stored in semi-conductor memory devices which were selected by simple digital logic units in response to a limited number of permissible user inputs. Addition of central computing units and more memory made increased variety and complexity possible, but it did not overcome the limitation to "stick men" and other simplistic displays.
Prior to this invention true interaction, using analog video pictures, was not available. It has been made available by the invention in a number of different forms.